Agent for stunting the growth of plants

ABSTRACT

A process for stunting the growth of plants with substituted pyridazinium compounds.

Umted States Patent 1 [111 3,736,121 Zeeh et al. [4 1 May 29, 1973 [54]AGENT FOR STUNTING THE GROWTH [58] Field of Search ..71/76, 92; OFPLANTS 260/250 A [75] Inventors: Bernd Zeeh, Ludwigshafen; Karl- HeinzKoenig, Frankenthal; Johann [56] References cued J ng, i rg f all f rm yUNITED STATES PATENTS 73 Assignee: Badische Ani|in & s r A 2,945,8577/1960 Hammann ..260/250 A tiengesellschaft, Ludwigshafen am RhineGermany Primary ExammerLew|s Gotls I Assistant Examiner-Catherine L.Mills Flledi 1971 Attorney-Johnston, Root, OKeeffe, Keil, Thompson 211-Appl. No.: 123,382 & Sh'mleff 30] Foreign Application Priority Data[57] ABSTRACT A process for stunting the growth of plants with sub- Apr.I. I970 Germany..; ..P 20 15 416.9 tituted yridazinium compounds, 52 US.Cl ..7l/76, 71/92, 260/250 A 4 C1aims,No Drawings [51] Int. Cl. ..A0ln9/22 dients substituted pyridazinium compounds.

lt is known to use nitrogenous compounds, such as chlorocholine chloride(CCC) (cf. Biol. Chem., 235, 475 to 479, 1960) andl-(B-chloroethyU-l,l-dimethylhydrazinium chloride (CMH) (K. -H. Konig,Naturwissenschaften, 55, 217 (1968))for stunting the growth of plants.However, their action is not always satisfactory.

We have now found that compounds of the formula m TA 1.1

where R, R R R and R may be identical or different and each denoteshydrogen, methyl, ethyl or isopropyl, and X denotes the anion of aninorganic or organic acid, stunt the growth height of numerous plants,especially cereals such as wheat, rye, barley and oats, but alsodicotyledoneae (e. g. tomatoes, vines, cotton) and various ornamentalssuch as poinsettia and hibiscus. The treated plants have a compact habitand a fairly dark leaf coloration.

It is the cation which determines the action of the compounds; almostany anion may be used. However, anions of phytotoxic acids should not beemployed if it is only intended to stunt the growth of the plants andnot to destroy them completely. Examples of suitable acids are:hydrochloric acid, hydrobromic acid, sulfuric acid, carbonic acid,nitric acid, phosphoric acid, acetic acid, propionic acid, benzoic acid,sulfuric acid monomethyl ester, sulfuric acid monoethyl ester, 2-ethylhexanoic acid, acrylic acid, maleic acid, succinic acid, adipicacid, formic acid, chloroacetic acid, p-toluenesulfonic acid, andbenzenesulfonic acid.

The compounds reach the plants either through root uptake or absorptionby the leaves. However, they may also be advantageously used inadmixture with conventional fertilizers and plant protection agents, andother carriers. To increase the action, wetting agents may also beadded. In addition to host soil and leaf treatment, it is possible todress the seed. As a result of the good plant compatibility, theapplication rate may vary considerably, e. g. up to kg per hectare.However, additions of 0.5 to 5 kg per hectare are generally sufficient.v

The compounds, some of which are new, may be prepared by variousmethods. As a rule, a partially alkylated hydrazine is used as startingmaterial and is reacted, in the presence of an oxidant, with a 1,3-dienein accordance with, for example, the following equation:

T III-CH: X

The preparation of an active ingredient is given below by way ofexample:

EXAMPLE 1 12 parts of 1,1-dimethy1hydrazine is dissolved in 50 parts of48 percent (by weight) aqueous hydrobromic acid and 50 parts of water.While stirring and at 0 C, 32 parts of bromine in parts of 48 percenthydrobromic acid and parts of water is added. The mixture issubsequently cooled to -10 C and 20 parts of butadiene is slowly added.Stirring is continued for 4 hours at l0 C. Two phases form andconcentration is effected in vacuo at 40 C. The residue isrecrystallized from isopropanol: 28 parts of 1,1-dimethyl-1,2,3,6-tetrahydropyridazinium bromide melting at 206 to 208 C is obtained.

The compound has the following structural formula:

NH ii I l-CH3 iHa The remaining compounds are prepared analogously;examples of other active ingredients are:

EXAMPLE 5 l,1-dimethyl-1,2,3,o-tetrahydropyridazinium ride, m.p.: 230 C(decomposes) chlo- EXAMPLE 61,l,2-trimethyl-1,2,3,5-tetrahydropyridazinium bromide, m.p.: 220 C.

The agents according to the invention may be used as solutions,emulsions, suspensions or dusts. The form of application dependsentirely on the purpose for which the agents are being used; in any caseit should ensure a fine distribution of the active ingredient.

For the preparation of solutions to be sprayed direct, the solution inwater is suitable. However, hydrocarbons having boiling points higherthan C, e. g. tetrahydronaphthalene or alkylated naphthalenes, ororganic liquids having boiling points higher than 150 C and having oneor more than one functional group, e. g. the keto group, the ethergroup, the ester group or the amide group, this group or these groupsbeing attached as substituent(s) to a hydrocarbon chain or being acomponent of a heterocyclic ring, may also be used as spray liquids.

Aqueous formulations may be prepared from emulsion concentrates, pastesor wettable powders by adding water. To prepare emulsions theingredients as such or dissolved in a solvent may be homogenized inwater or organic solvents by means of wetting or dispersing agents, e.g. polyethylene oxide adducts. Concentrates which are suitable fordilution with water may be prepared from active ingredient, emulsifyingor dispersing agent and possibly solvent.

Dusts may be prepared by mixing or grinding the active ingredients witha solid carrier, e. g. kieselguhr, talc, clay or fertilizers.

In the following examples, the action of l, l-dimethyll,2,3,o-tetrahydropyridazinium bromide (DMP) on various plantsis shown.

EXAMPLE 7 ln Neubauer dishes (glass vessels having a diameter of l 1.5cm) the cereals wheat (Opal type), barley (Breuns Wisa type) and rye(Petkuser type) were sown in a sandy loam soil which had previously beenadequately supplied with nutrients. The application rates were 3, 6 and12 mg of active ingredient per dish, corresponding to preemergenceapplication rates of 3, 6 and 12 kg per hectare of active ingredient.The prior art growth regulators CCC (2-chloroethyltrimethylammoniumchloride) and CMH (l-(B-chloroethyU-Lldimethylhydraz onium chloride)were used in the experiment for comparison purposes.

The plants were continuously observed in the greenhouse for a period of5 weeks. Emergence was normal at all application rates. After only aweek differences were observed: DMP had, compared with CCC and CMH, asuperior action, particularly on barley and rye. The chlorophyll content(leaf coloration) .was most strongly influenced by the active ingredientaccording to the invention.

After 5 weeks the height of the plants was measured; the results aregiven in the following table. As these figures show, DMP wasconsiderably superior to the agents used for comparison purposes.

A. Action on wheat (Opal) Active ingredient Application rate Plantheight kg/ha in cm relative untreated (control) 28.5 I

CMH 3 2o 70 CMH 6 11.5 6|

CMH 12 155 a DMP 3' 19.5 as DMP 6 111 s:

DMP 12 1s 56 B. Action on barley (Bruen's Wisa) Active ingredientApplication rate- Plant height kg/ha in cm relative untreated (control)28 I00 ccc 225 so ccc a 21 1s ccc 12 1o 71 CMH 3 2: 112

CMH 5 22.5 110 CMH 12 2l 75 DMP 3 2|.5 77 DMP 6 20 71 DMP l2 I9 68 C.Action on rye (Petkuser) Active ingredient Application rate Plant heightkg/ha in cm relative untreated (control) 23.5 I00 ccc :1 22 94 ccc a21.5 92 ccc 12 20 as CMH J 21.5 92 CMH s 21 119 DMP 12 2| DMP 6 [9.5 DMPl2 I9 EXAMPLE 8 parts by weight of the compound of Example 1 is mixedwith 30 parts by weight of Nmtethyl-apyrrolidone. A mixture is obtainedwhich is suitable for application in the form of very fine drops.

EXAMPLE 9 20 parts by weight of the compound of Example 2 is dissolvedin a mixture consisting of parts by weight of xylene, 10 parts by weightof the adduct of 8 to 10 moles of ethylene oxide to 1 mole of oleicacid-N- monoethanolamide, 5 parts by weight of the calcium salt ofdodecylbenzenesulfonic acid, and 5 parts by weight of the adduct of 40moles of ethylene oxide to 1 mole of castor oil. By pouring the solutioninto 100,000 parts by weight of water and uniformly distributing ittherein, an aqueous dispersion is obtained containing 0.02 percent byweight of the active ingredient.

EXAMPLE 10 EXAMPLE 1 l 20 parts by weight of the compound of Example 4is dissolved in a mixture consisting of 25 parts by weight ofcyclohexanol, 65 parts by weight of a mineral oil fraction having aboiling point between 210 and 280 C, and 10 parts by weight of theadduct of 40 moles of ethylene oxide to 1 mole of castor oil. By pouringthe solution into 100,000 parts by weight of water and uniformlydistributing it therein, an aqueous dispersion is obtained containing0.02 percent by weight of the active ingredient.

EXAMPLE 12 20 parts by weight of the compound of Example 5 is well mixedwith 3 parts by weight of the sodium salt ofdiisobutylnaphthalene-a-sulfonic acid, 17 parts by weight of the sodiumsalt of a lignin-sulfonic acid obtained from a sulfite waste liquor, and60 parts by weight of powdered silica gel, and triturated in a hammermill. By uniformly distributing the mixture in 20,000 parts by weight ofwater, a spray liquid is obtained containing 0.l percent by weight ofthe active ingredient.

EXAMPLE l3 3 parts by weight of the compound of Example 1 is intimatelymixed with 97 parts by weight of particulate kaolin. A dust is obtainedcontaining 3 percent by weight of the active ingredient. i

EXAMPLE 14 30 parts by weight of the compound of Example 1 is I L-CHaCH:

where R, R R, R and R may be identical or different and each denoteshydrogen or methyl, ethyl or isopropyl, and X denotes the anion of aninorganic or organic acid.

2. A process for stunting the growth of plants wherein 1,1-dimethyl-l,2,3.,o-tetrahydropyridazinium bromide is used as active ingredient.

3. A process as claimed in claim 1 wherein the host soil is treated withsaid effective amount of said compound.

4. A process as claimed in claim 1 wherein said amount is in the rangeof 0.5 to 15 kg. per hectare.

2. A process for stunting the growth of plants wherein1,1-dimethyl-1,2,3,6-tetrahydropyridazinium bromide is used as activeingredient.
 3. A process as claimed in claim 1 wherein the host soil istreated with said effective amount of said compound.
 4. A process asclaimed in claim 1 wherein said amount is in the range of 0.5 to 15 kg.per hectare.